Sixth Edition 3.11

[904901860]

I'm confused as to why it would be a.) Co+3 and b.) Fe3+ instead of a.) Fe+3 and b.)Mn +3

[Jeremy_Guiman2E]

So for a and b of this problem, we're given: (a) [Ar]3d⁶; (b) [Ar]3d⁵ (and that these are M³⁺ where M is a metal).

This means that to find the neutral atom (so we know which element we're looking for) we'd need to look for the electron configuration with 3 more electrons than what we were given (accounting for the 3+ charge).

-in part a, this would be a configuration of [Ar]4s²3d⁷. This is Co, which is why for the ionized structure [Ar]3d⁶ we'd get Co³⁺.

-in part b, this would be a configuration of [Ar]4s²3d⁶. This is the typical configuration for Fe, which is why for the ionized structure [Ar]3d⁵ we'd get Fe³⁺.